The invention relates generally to tube configurations for multichannel heat exchangers.
Heat exchangers are used in heating, ventilation, air conditioning, and refrigeration (HVAC&R) systems. Multichannel heat exchangers generally include multichannel tubes for flowing refrigerant through the heat exchanger. Each multichannel tube may contain several individual flow channels, or paths. Fins may be positioned between the tubes to facilitate heat transfer between refrigerant contained within the flow paths and an external fluid passing over the tubes. Moreover, multichannel heat exchangers may be used in small tonnage systems, such as residential systems, or in large tonnage systems, such as industrial chiller systems.
A typical multichannel heat exchanger may include several multichannel tubes, each protruding into inlet and outlet manifolds at relatively equal depths. Refrigerant may enter the inlet manifold through an inlet, and as the refrigerant flows through the manifold, a portion of the refrigerant may be diverted into each of the multichannel tubes. The refrigerant volumetric flow rate may be the highest near the manifold refrigerant inlet, and the flow rate may decrease as the refrigerant enters the multichannel tubes, successively farther from the position of the manifold inlet. However, because the diameter of the manifold remains substantially constant along the length of the manifold, the refrigerant may experience a pressure drop near the inlet. Specifically, because typical heat exchangers employ multichannel tubes having substantially rectangular ends inserted within the inlet manifold at relatively equal depths, a small flow area is formed near the refrigerant inlet. This small flow area may induce a pressure drop within the inlet manifold, thereby reducing efficiency of the heat exchanger. Accordingly, it would be desirable to provide a larger flow area near the refrigerant inlet to reduce the pressure drop through the inlet manifold.